Eudidymite
A valid IMA mineral species - grandfathered
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About Eudidymite
Formula:
Na2Be2Si6O15 · H2O
Colour:
White, colorless
Lustre:
Vitreous, Pearly
Hardness:
6
Specific Gravity:
2.55
Crystal System:
Monoclinic
Name:
From the Greek words for well and twinned, in allusion to its common occurrence in twins.
Type Locality:
Dimorph of:
During his visit in the summer of 1887 to Lille Arøya, Langesundsfjorden in Norway, the mineralogist Waldemar Christofer Brøgger (1851-1940) was shown an unknown mineral found by two local collectors. It was showed to be a new mineral and later described by Brøgger (1887, 1890).
The crystal structure was solved by Ito (1947) and Fang et al. (1972).
Note: The type locality, the island Lille Arøya, was called by Brøgger as Ober-Arö or Övre Arö. The contemporary correct name is Lille Arøya.
The crystal structure was solved by Ito (1947) and Fang et al. (1972).
Note: The type locality, the island Lille Arøya, was called by Brøgger as Ober-Arö or Övre Arö. The contemporary correct name is Lille Arøya.
Unique Identifiers
Mindat ID:
1421
Long-form identifier:
mindat:1:1:1421:8
GUID
(UUID V4):
(UUID V4):
e3c1a915-23df-48f2-944c-13f741a8f9e7
IMA Classification of Eudidymite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1887
Classification of Eudidymite
9.DG.60
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
66.3.1.3
66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
3 : Amphiboles - Ca-Na subgroup
66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
3 : Amphiboles - Ca-Na subgroup
14.3.6
14 : Silicates not Containing Aluminum
3 : Silicates of Be
14 : Silicates not Containing Aluminum
3 : Silicates of Be
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Symbol | Source | Reference |
---|---|---|
Edy | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Eudidymite
Vitreous, Pearly
Transparency:
Transparent, Translucent
Comment:
Pearly on cleavages
Colour:
White, colorless
Streak:
White
Hardness:
6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {001}, imperfect on{551}
Perfect on {001}, imperfect on{551}
Density:
2.55 g/cm3 (Measured)
Optical Data of Eudidymite
Type:
Biaxial (+)
RI values:
nα = 1.545 nβ = 1.546 nγ = 1.551
2V:
Measured: 30° , Calculated: 50°
Max Birefringence:
δ = 0.006
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
r > v distinct
Chemistry of Eudidymite
Mindat Formula:
Na2Be2Si6O15 · H2O
Common Impurities:
Al,Fe,Ca
Crystallography of Eudidymite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Cell Parameters:
a = 12.6188(10) Å, b = 7.3781(5) Å, c = 13.9940(9) Å
β = 103.762(5)°
β = 103.762(5)°
Ratio:
a:b:c = 1.71 : 1 : 1.897
Unit Cell V:
1265.47 ų
Z:
4
Morphology:
Crystals tabular on (001), spherulitic, micaceous, coarse and granular,massive.
Twinning:
Twins on {001} common. V-shaped (Swallowtwins) twin
Crystallographic forms of Eudidymite
Crystal Atlas:
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
---|---|---|---|---|---|---|---|
0000043 | Eudidymite | Ito T (1947) The structure of eudidymite (HNaBeSi3O8) American Mineralogist 32 442-453 | 1947 | 0 | 293 | ||
0000293 | Eudidymite | Fang J H, Robinson P D, Ohya Y (1972) Redetermination of the crystal structure of eudidymite and its dimorphic relationship to epididymite American Mineralogist 57 1345-1354 | 1972 | 0 | 293 | ||
0004615 | Eudidymite | Gatta G D, Rotiroti N, McIntyre G J, Guastoni A, Nestola F (2008) New insights into the crystal chemistry of epididymite and eudidymite from Malosa, Malawi: A single-crystal neutron diffraction study American Mineralogist 93 1158-1165 | 2008 | Malosa, Malawi | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
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Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
3.163 Å | (10) |
3.398 Å | (8) |
3.074 Å | (8) |
6.35 Å | (6) |
2.999 Å | (6) |
2.848 Å | (6) |
3.687 Å | (5) |
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 4a: Earth’s earliest continental crust | >4.4-3.0 |
19 : Granitic intrusive rocks | |
Stage 4b: Highly evolved igneous rocks | >3.0 |
35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Eudidymite
General Appearance of Type Material:
Tabular crystals, usually twinned on {001}
Chemical Analysis of Type Material:
SiO2 | 73.11 % |
---|---|
BeO | 10.42 % |
Na2O | 12.24 % |
MgO | traces % |
H2O | 3.79 % |
Total: | 99.56 % |
Geological Setting of Type Material:
Nepheline syenite
Associated Minerals at Type Locality:
Reference:
Brøgger, W.C. (1887). Om ”Eudidymit”, et nyt norsk mineral. Forelöbig meddelelse. Nyt Magazin for Naturvidenskaberne, 31, 196-199
Other Language Names for Eudidymite
Common Associates
Associated Minerals Based on Photo Data:
61 photos of Eudidymite associated with Aegirine | NaFe3+Si2O6 |
34 photos of Eudidymite associated with Epididymite | Na2Be2Si6O15 · H2O |
13 photos of Eudidymite associated with Quartz | SiO2 |
12 photos of Eudidymite associated with Microcline | K(AlSi3O8) |
12 photos of Eudidymite associated with Smoky Quartz | SiO2 |
10 photos of Eudidymite associated with Natrolite | Na2Al2Si3O10 · 2H2O |
7 photos of Eudidymite associated with Analcime | Na(AlSi2O6) · H2O |
7 photos of Eudidymite associated with Leucophanite | NaCaBeSi2O6F |
6 photos of Eudidymite associated with Dolomite | CaMg(CO3)2 |
5 photos of Eudidymite associated with Albite | Na(AlSi3O8) |
Related Minerals - Strunz-mindat Grouping
9.DG. | Calcinaksite | KNaCa(Si4O10) · H2O |
9.DG. | Barrydawsonite-(Y) | Na1.5Y0.5CaSi3O8(OH) |
9.DG. | Paratobermorite | Ca4(Al0.5Si0.5)2Si4O16(OH)(H2O)2 · (Ca · 3H2O) |
9.DG. | Alvesite | NaKZrSi6O15 · 2H2O |
9.DG.02 | Steedeite | NaMn2[Si3BO9](OH)2 |
9.DG.02 | Nolzeite | NaMn2[Si3BO9](OH)2 · 2H2O |
9.DG.05 | Bustamite | CaMn2+(Si2O6) |
9.DG.05 | Ferrobustamite | CaFe2+(Si2O6) |
9.DG.05 | Pectolite | NaCa2Si3O8(OH) |
9.DG.05 | Serandite | NaMn2+2Si3O8(OH) |
9.DG.05 | Wollastonite | Ca3(Si3O9) |
9.DG.05 | Wollastonite-1A | CaSiO3 |
9.DG.05 | Tanohataite | LiMn2Si3O8(OH) |
9.DG.05 | Schizolite | NaCaMnSi3O8(OH) |
9.DG.05 | Murakamiite | LiCa2Si3O8(OH) |
9.DG.05 | Dalnegorskite | Ca5Mn(Si3O9)2 |
9.DG.07 | Cascandite | CaScSi3O8(OH) |
9.DG.08 | Plombièrite | [Ca4Si6O16(OH)2 · 2H2O] · (Ca · 5H2O) |
9.DG.10 | Clinotobermorite | [Ca4Si6O17 · 2H2O] · (Ca · 3H2O) |
9.DG.10 | Riversideite | Ca5(HSi3O9)2 · 2H2O |
9.DG.10 | Tobermorite | Ca4Si6O17(H2O)2 · (Ca · 3H2O) |
9.DG.12 | Jusite | Na2Ca15Al4Si16O54 · 17H2O |
9.DG.12 | Kenotobermorite | Ca4Si6O15(OH)2(H2O)2 · 3H2O |
9.DG.15 | Foshagite | Ca4(Si3O9)(OH)2 |
9.DG.20 | Jennite | Ca9(Si3O9)2(OH)8 · 8H2O |
9.DG.20 | Kamenevite | K2TiSi3O9 · H2O |
9.DG.25 | Paraumbite | K3Zr2H(Si3O9)2 · nH2O |
9.DG.25 | Umbite | K2(Zr,Ti)Si3O9 · H2O |
9.DG.30 | Sørensenite | Na4SnBe2Si6O16(OH)4 |
9.DG.32 | Escheite | Ca2NaMnTi5[Si12O34]O2(OH)3 · 12H2O |
9.DG.35 | Xonotlite | Ca6(Si6O17)(OH)2 |
9.DG.40 | Hillebrandite | Ca2(SiO3)(OH)2 |
9.DG.45 | Zorite | Na8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2O |
9.DG.45 | Chivruaiite | Ca4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2O |
9.DG.50 | Haineaultite | (Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2O |
9.DG.55 | Epididymite | Na2Be2Si6O15 · H2O |
9.DG.65 | Elpidite | Na2ZrSi6O15 · 3H2O |
9.DG.65 | Patynite | NaKCa4[Si9O23] |
9.DG.67 | Whelanite | Cu2+2Ca6[Si6O17(OH)](CO3)(OH)3 · 2H2O |
9.DG.70 | Fenaksite | (K,Na)4(Fe,Mn)2(Si4O10)2(OH,F) |
9.DG.70 | Litidionite | CuNaKSi4O10 |
9.DG.70 | Manaksite | KNaMnSi4O10 |
9.DG.70 | Yusupovite | Na2Zr(Si6O15) · 2.5H2O |
9.DG.70 | Enricofrancoite | KNaCaSi4O10 |
9.DG.75 | Tinaksite | K2Na(Ca,Mn2+)2TiO[Si7O18(OH)] |
9.DG.75 | Tokkoite | K2Ca4[Si7O18(OH)](OH,F) |
9.DG.75 | Senkevichite | CsKNaCa2TiO[Si7O18](OH) |
9.DG.80 | Canasite | K3Na3Ca5Si12O30(OH)4 |
9.DG.80 | Fluorcanasite | K3Na3Ca5Si12O30F4 · H2O |
9.DG.85 | Miserite | K1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2O |
9.DG.90 | Frankamenite | K3Na3Ca5(Si12O30)(F,OH)4 · H2O |
9.DG.92 | Charoite | (K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O |
9.DG.95 | Yuksporite | K4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3 |
9.DG.97 | Eveslogite | (Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Eudidymite
mindat.org URL:
https://www.mindat.org/min-1421.html
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References for Eudidymite
Reference List:
Flink, G (1899) Über einige seltene Mineralien aus der Gegend von Langesund in Norwegen [About some rare minerals from the Langesund area in Norway]. Bulletin of the Geological Institution of the University of Upsala, 4. 16-27
Fang, J. H., Robinson, Paul D., Ohya, Y. (1972) Redetermination of the crystal structure of eudidymite and its dimorphic relationship to epididylnite. American Mineralogist, 57 (9-10) 1345-1354
Shannon, Robert D., Shannon, Ruth C., Medenbach, Olaf, Fischer, Reinhard X. (2002) Refractive Index and Dispersion of Fluorides and Oxides. Journal of Physical and Chemical Reference Data, 31 (4) 931-970 doi:10.1063/1.1497384
Localities for Eudidymite
Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
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Eudidymite locality, Lille Arøya, Larvik, Vestfold, Norway